Page 1 of 1
Differences between Join, Merge and Lookup Stages.
Posted: Tue Dec 26, 2006 7:29 am
by Abhijeet1980
Dear All,
Can anyone outline the differences between Join, Merge and Lookup Stages ?
I've read a few forum messages regarding Join, Merge and Lookup, but have found no satisfactory answers.
Senior members: Pls do respond....
Posted: Tue Dec 26, 2006 7:42 am
by chulett
Have you tried... oh, I don't know... reading the Parallel Job Developer's Guide pdf? Each stage has its own lovely little chapter in there.
Posted: Tue Dec 26, 2006 3:17 pm
by ray.wurlod
If you attend the IBM DataStage Essentials class there is one page in the student guide that does attempt a summary of the differences between these three stage types.
How about you make your own summary, based on reading the manual, and we can comment on that? You see, different things are important to different people - you might be interested in functionality, while someone else might be interested in resource consumption. Someone else might just need others to supply an answer to an interview question, which is something we try to avoid doing here.
Posted: Tue Dec 26, 2006 5:38 pm
by kumar_s
Code: Select all
Join Lookup Merge
Description RDBMS-style Source and lookup Master table and one
Relational tables table in RAM or more update tables
Number and names 2 or more inputs 1 source and N lookup 1 master tables and N
Of inputs tables update tables
Memory usage Light Heavy Light
Handling of Ok, produces a OK Warning given
duplicates in Cross-product Duplicates will be an
primary input unmatched primary.
Handling of Ok, produces a Warning given. The Ok only when N =1
duplicates in Cross-product second lookup table
secondary input entry is ignored.
Options on
Unmatched None None Capture in reject sets.
secondary
On match, secondary reusable reusable reusable
entriesare
Number of outputs 1 1 output and 1 output and 1 reject for
optionaly 1 reject each update table
Captured in reject Does not apply Unmatched primary Unmatched Secondary entries
Set entries
Posted: Tue Dec 26, 2006 5:42 pm
by DSguru2B
Good going Kumar. Great post. Everything in a nice table like format. We like tables, we are dw guys after all
Posted: Tue Dec 26, 2006 5:47 pm
by kumar_s
True, aligning to this format took a long. Atleast once.
Posted: Tue Dec 26, 2006 5:50 pm
by narasimha
Nice effort Kumar!
Is this from the IBM DataStage Essentials class or did you compile it yourself? Thanks for sharing it.
Posted: Tue Dec 26, 2006 5:57 pm
by kumar_s
I have posted it already, so I guess I might have taken it from Orchestrate manuals.
Posted: Tue Dec 26, 2006 6:00 pm
by ray.wurlod
It's quite like the table in the DataStage Essentials class, though missing the row that indicates whether sorted inputs are required.
Posted: Tue Dec 26, 2006 6:04 pm
by kumar_s
Ray you shall add you valuable inputs to this thread, which will be useful for those who have not access to DataStage Essentials class.
Posted: Tue Dec 26, 2006 6:13 pm
by narasimha
kumar_s wrote:I have posted it already, so I guess I might have taken it from Orchestrate manuals.
No sweat, Just appreciations for your efforts
Posted: Tue Dec 26, 2006 6:21 pm
by ray.wurlod
kumar_s wrote:Ray you shall add you valuable inputs to this thread, which will be useful for those who have not access to DataStage Essentials class.
Everyone has access to IBM training, in exchange for money.
(The original post still smells like an interview question to me.)
Posted: Tue Jan 02, 2007 6:50 am
by Abhijeet1980
Thanx very much for sharing wonderful information with me.
The comparision was really wonderful.
Regards
Abhijit